Epistles

Paul Barnett has a very helpful paragraph in his commentary in the NICNT series in which he charts the main line through the 8th and 9th chapters of 2 Corithians:

A few quotations from Douglas Moo's Commentary on the book of James to fill in a bit more background to the material we looked at during Kemsing's Useful! service on the second half of James 2.

I'm greatly enjoying spending some time in Paul's letter to the Philippians, in preparation for the first of our new quarterly combined services. The two churches (Kemsing and Woodlands) will come together for a shared Communion service 4 times a year. I am really looking forward to the occasion. In many respects, the two churches are very different. However the riches we share in Christ are many, and this quarterly celebration will be the chance to rejoice in that and to commit afresh to serving together in holding out the word of Christ.

I've long found 1 Peter 3:19-22 really hard to understand. Much attention gets given to questions like who the spirits in prison are and so on. However my concern is to understand Peter's flow of thought throughout 1 Peter 3:18-22. 3:18 would flow nicely into 4:1 (“For Christ also suffered once for sins… made alive in the Spirit. Since therefore Christ suffered in the flesh, arm yourselves also with the same attitude.”), so why does Peter insert 3:19-22 in between here?